The disclosure of Japanese Patent Application No. 2001-232297 filed on Jul. 31, 2001, including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The invention relates to a visibility assist device and method that provides a vehicle operator an image of a road that is difficult to see when driving at night.
2. Description of Related Art
Vehicle visibility assist devices are known. A known device projects light to an area outside a vehicle when it is determined that it is dark outside the vehicle based on detection results from a brightness sensor.
The conventional visibility assist device is activated when it is determined that it is dark outside the vehicle, based on detection results of the brightness sensor. However, the level of darkness in which this kind of visibility assistance is considered necessary differs from individual to individual, and can vary according to light conditions, driving conditions and so on. To leave allowance for these factors, therefore, the visibility assist device may activate while it is still relatively light outside. When this occurs, the amount of time that the visibility assist device is in operation is increased unnecessarily. This increases the amount of power consumed and shortens the life of the system.
It is preferable, therefore, to activate the visibility assist device only when the vehicle operator deems it to be truly necessary. Setting activation conditions to accomplish this result, however, has proven difficult. Because of this problem, conventional visibility assist devices occasionally have not activated under conditions where activation should have occurred, making it difficult for the user to tell whether the device is operating normally.
The invention has as one object to provide a visibility assist device in which the frequency of unnecessary operation is reduced, and which is capable of reliably activating when deemed necessary by the vehicle operator.
An apparatus according to the invention is provided with a visibility assist device that provides an image outside a vehicle captured by irradiation of an infrared light, a brightness sensor that detects a level of brightness outside the vehicle, and a controller that detects a selected position of a switch of an illumination device that illuminates an area outside the vehicle, and controls startup of the visibility assist device such that the visibility assist device is started when the detected brightness is below a predetermined level and the detected position of the switch of the illumination device of the vehicle indicates that the illumination device has turned on.
When a switch operation to turn on an illumination device, such as a headlight, so as to illuminate the area outside the vehicle is detected, it is assumed that the vehicle operator subjectively feels that it is dark outside. Therefore, the controller starts up the visibility assist device upon establishment of two conditions; i) the illumination device switch position indicates that the vehicle operator subjectively feels it is dark outside the vehicle, and ii) it is objectively determined from detection results of the controller that it is dark outside the vehicle. Having the visibility assist device start up based on these two conditions reduces the frequency of unnecessary operation, and enables the device to turn on when truly necessary, compared with the case where the device is turned on based on establishment of only one of the aforementioned conditions.
The apparatus further includes a main switch that is placed in a selected one of at least two states. The two states include a first state in which startup of the visibility assist device is permitted, and a second state in which startup of the visibility assist device is prohibited. The controller starts up the visibility assist device when the main switch is switched to the first state.
In this way, the controller determines i) whether the vehicle operator subjectively feels that it is dark outside in view of operation of the main switch, ii) whether it is objectively dark outside the vehicle, and iii) whether the vehicle operator intends to use the visibility assist device, i.e., whether there is a need for visibility assistance. The controller therefore starts up the visibility assist device under conditions where its use is truly necessary.
The apparatus further includes an illumination control device that automatically turns on and off the illumination device in accordance with the brightness outside the vehicle, detected by the brightness sensor.
In this way, the brightness detecting unit is used for the controller and the light control system to detect the brightness outside the vehicle. Therefore it is possible to keep the number of parts from increasing and thus keep manufacturing costs down.
In the apparatus, the illumination device preferably is a headlight, and the controller detects a switching operation for turning on and off the headlight. However, the invention is not limited to use with a headlight.
The vehicle operator turns on the headlights when he or she finds it difficult to see the road because it is dark outside the vehicle. Accordingly, the visibility assist device regards a switch operation to turn the headlights on as a sign that it is difficult to see the road because of darkness, and therefore the visibility assist device is deemed necessary. Detection of the illumination device switch operation is used for each of the startup controls described above, thereby enabling the visibility assist device to be started up appropriately when necessary.
An apparatus according to the invention is provided with a visibility assist device that provides an image outside of a vehicle captured by irradiation of an infrared light, an infrared light projecting unit that projects an infrared light to a predetermined region outside the vehicle so as to capture a reflected image of the predetermined region outside the vehicle, and a controller that detects a selected position of a switch of a lighting unit of the vehicle and controls turning the infrared light projecting unit on and off such that the infrared light projecting unit is turned off when it is determined that the lighting unit is in a high-beam state.
For example, the illumination device, such as a headlight, can be configured so as to have two light projecting states; i) a low beam state for lighting an area a relatively short distance in front of the vehicle, and ii) a high beam state for lighting an area a relatively long distance in front of the vehicle, and can be switched between the two states with a switch. Also, as the light irradiated from this type of lighting device includes infrared light, it is also possible to provide an infrared view of a region outside the vehicle by obtaining reflected infrared light from an area to be imaged that is a long distance away by using the high beams to light that region. Therefore, when the illumination device is in the high beam state, the light control device turns off the infrared projecting unit, and an infrared image based on the reflected light of the high beams is obtained such that power consumption is reduced. Although the above discussion relates to vehicle headlights, the invention is not limited to using headlights as the illumination device, and also is not limited to lighting a region in front of the vehicle.
The apparatus is further provided with a brightness sensor that detects brightness outside the vehicle. The controller of the apparatus controls startup of the visibility assist device such that the visibility assist device is started when the detected brightness is lower than a predetermined level and the detected position of the switch of the lighting unit of the vehicle indicates turning the illumination device has been turned on.
When the illumination device is in the high beam state, the light control device turns off the infrared projecting unit so that power consumption is reduced. The controller starts up the visibility assist device upon establishment of two conditions; i) the vehicle operator subjectively feels that it is dark outside, and ii) it is objectively determined based on detection results from the brightness sensor that it is dark outside the vehicle. Having the visibility assist device start up based on these two conditions reduces the frequency of operation of the device, as well as enables the device to start up when truly necessary, compared with being started up based on only one of the aforementioned conditions.
The apparatus is further provided with a first indicator that indicates an operating state of the visibility assist device and a second indicator that indicates whether the infrared light projecting unit is turned on or turned off when the visibility assist device is in the operating state.
By providing the first indicator and the second indicator, it is possible to prevent the vehicle operator from incorrectly assuming that the infrared light projecting device is malfunctioning, when the infrared light projecting device is off during operation of the visibility assist device, just as with the visibility assist device.
The apparatus is further provided with a projecting unit that projects a view of the outside of the vehicle captured by the infrared light onto a projection surface that faces a vehicle operator, and a movable cover member capable of covering the projecting unit.
The projecting function of the projecting unit that projects an infrared view of a region outside of the vehicle may be damaged if directly exposed to sunlight for an extended period of time. Accordingly, covering the projecting unit with a movable cover member when the visibility assist device is not in use protects the projecting unit from direct sunlight.
In the apparatus, the projecting unit projects the infrared light directly to the projection surface.
When the projecting unit is positioned so as not to be exposed to direct sunlight, there may be cases in which an infrared image is unable to be projected from the projecting unit directly onto the projection surface because of the position of the projecting unit. In this case, a light path adjusting member can be provided between the projecting unit and the projection surface, for example. Having the projecting unit project the infrared image directly onto the projection surface without using the aforementioned light path adjusting member, reduces the number of parts, helping to simplify the system configuration.
In the apparatus, the projection surface is a windshield, below which the projecting unit is provided.
In the aforementioned aspect, the windshield serves as the projection surface and the projecting unit is arranged below the projection surface. It is possible to provide a visibility assist device which has superior mountability so as to make effective use of limited mounting space and which is also highly visible by the vehicle operator.